Exploring the nonlinear stochastic dynamics of an orchard sprayer tower moving through an irregular terrain
Résumé
In agricultural industry, the process of orchards spraying is of extreme importance for pest control. The non control of pests can lead to problems such as: (i) reduction of quality in the agricultural products, which is bad for the consumer; (ii) partial or total loss of the plantation, which causes huge financial losses to the producer. In orchards spray process it is used an agricultural equipment, called sprayer, that consists of a reservoir and fans, these being mounted over an articulated tower, which is supported by a vehicle suspension [1]. This equipment is subject to a load of random nature, due to soil irregularities, which may hamper the proper dispersion of the fluid spraying. This work presents the construction of a consistent stochastic model of uncertainties to describe the non-linear dynamic behaviour of an orchard sprayer tower, subjected to random excitations due to soil irregularities. In this model, the mechanical system is described as an inverted pendulum over a vehicle suspension, and the random loadings are assumed to be a harmonic random process, with random amplitude and frequency [2, 3]. Uncertainties are take into account through a parametric probabilistic approach, where maximum entropy principle is used to consistently construct the distribution of the random parameters, and Monte Carlo method is employed to compute the propagation of uncertainties through the stochastic model. Numerical simulations show that this system may present periodic, and chaotic behaviour, and highlight large discrepancies in the stochastic system response, when compared with nominal (deterministic) model [2–4].